大容量火电机组调峰运行的轴系振动特性分析

发布时间：2018-06-08 08:01

本文选题：大容量火电机组 + 轴系振动特性　；参考：《华北电力大学》2014年博士论文

【摘要】：随着我国经济的快速发展,用电负荷的峰谷差逐渐增大。近些年来,针对越来越高的节能环保要求,我国火力发电设备经过了上大压小的产业结构调整,投运了大量600MW及以上的大容量火电机组。我国新能源发电的快速发展,也对电网的负荷变化产生新影响。在这种背景下,参与调峰运行的火电机组容量不断增加,许多大容量火电机组也投入到调峰运行的行列,根据电网的负荷需求在较大范围内进行负荷调节。火电机组参与宽负荷范围调峰运行的关键问题是对电网负荷快速变化的适应性和低负荷下运行的稳定性。我国大容量火电机组通常以承担中问负荷为主进行设计,这类机组参与调峰运行,由于运行工况条件发生变化,出现较多极端运行工况,可能带来轴系结构热应力、变形、轴系振动和稳定性等方面的新问题,导致设备存在重大安全隐患。提高大容量火电机组在宽范围负荷快速变动条件下的运行安全性是发电行业急需解决的关键技术问题。大容量火电机组参与调峰所带来的运行安全稳定性问题在我国更加突出,原因是我国在机网两侧的条件与西方国家存在差异,而这方面尚缺少深入的研究。本文针对大容量火电机组的特殊性,以600MW汽轮发电机组为对象,在国家和企业科技项目的支持下,深入开展大范围变负荷运行条件下的机组轴系动态特性与稳定性、故障状态下的振动特性及故障特征提取方法等方面的研究,对于提高机组参与调峰运行的安全可靠性具有重要的科学和工程实际意义。论文的主要研究内容及成果如下： (1)600MW机组结构及运行特点分析。结合两个细则,分析了AGC运行方‘式对汽轮机寿命、材料及轴系振动特性的影响,对大容量火电机组振动监测保护系统(TSI系统和TDM系统)的技术现状进行综述；针对某600MW亚临界火电机组,利用实际运行数据分析了自动发电控制(AGC)运行方式下,机组负荷、主汽压力、主汽流量变化对于汽轮机轴系振动的扰动。从运行数据反映的长期趋势看,机组快速变化负荷对高中压缸两端轴承振动产生一定影响。从瞬态振动数据分析来看,负荷变化对振动信号波形、频谱构成影响不明显,没有改变高中压转子的振动状态。 (2)轴系振动特性的计算分析。以国产典型600MW火电机组为对象,分别用传递矩阵法和有限元法对轴系弯振和扭振固有特性、快速变负荷状态下的轴系扭振响应特性、发电机两相短路故障下的轴系扭振响应特性进行了仿真计算和比较研究。分析结果表明,600MW机组的轴系扭振危险轴段均位于各转子之间的连接部位：在快速升降负荷时,轴系扭矩响应呈现衰减振荡特性,表明机组在快速升负荷时轴系处于稳定状态；两相短路故障的扭矩响应中,一、二阶扭振固有频率处的峰值最突出,工频及其二次谐波也比较明显,存在共振风险。因此两相短路故障对轴系安全性影响较大。 (3)汽轮机瞬态过程的轴系异常振动分析。通过实际案例,对大容量火电机组出现的异常振动现象进行分析,探讨异常振动的响应特性,研究提取故障特征的信号分析方法,为进行轴系故障诊断提供依据。研究了某600MW机组高中压转子发生的缓慢热变形现象的振动特征,确定了导致转子热变形的原因,。提出了一种基于Gabor变换时频域滤波的提取振动信号中特殊频率成分,进行轴系稳定性分析和故障判断的方法。通过对升降速过程的振动信号、气流激振导致的不稳定振动信号的分析,证明了该方法的效果。 (4)汽轮机碰磨故障监测诊断方法研究。汽轮发电机组发生轻微动静部件碰磨故障时,相对轴振响应信号中的故障信息非常微弱。针对这一特点,提出采用结构振动检测和信号分析处理相结合的碰磨故障监测诊断新方法,该方法利用碰磨引起的较高频率的冲击振动能量信息,适用于碰磨这类具有瞬时冲击特征的异常振动。由于相对轴振监测对碰磨引起的冲击振动响应不敏感,提出一种采用小波奇异值检测碰磨冲击故障的方法,用小波多分辨率分析获取在特定尺度上的碰磨瞬时冲击信号,提取该瞬时冲击信号的幅值包络,然后采用小波奇异值检测方法对碰磨引起的突变信息进行检测,可以明显改善微弱碰磨故障特征的提取效果。 (5)汽轮机振动源的盲分离方法研究。采用频域ICA分析方法对多台大容量汽轮机组进行了多通道轴振信号振源分离,结果表明频域ICA能够更清楚地给出源信号的描述,分离结果更符合汽轮机转子系统振动源的实际情况。频域ICA可以分离出轴振测量信号中包含的可能很微弱的故障信息,分离结果的物理意义比较清晰明确。研究了利用单通道振动实测信号的ICA特征提取方法,结果表明,仅仅依靠单通道ICA分离出的基函数不足以反映机组运行状态的变化,需要进一步对各个基函数进行处理,验证其作为特征信息的有效性。
[Abstract]:With the rapid development of China's economy, the peak and valley difference of electric load has gradually increased. In recent years, in view of the increasing demand for energy saving and environmental protection, China's thermal power generation equipment has been adjusted to the large pressure and small industrial structure, and a large number of large capacity thermal power units have been transported to 600MW and above. Load change has a new effect. Under this background, the capacity of thermal power units involved in peak load regulation is increasing, and many large capacity thermal power units are also put into the ranks of peak load regulation. Load regulation is carried out in a large range according to the load demand of power grid. The key problem of the power generating unit to participate in the wide negative load range regulation is the negative power grid. The capacity of large capacity thermal power units in China is usually designed by the medium load, which is involved in peak load regulation. Because of the change of operating conditions, many extreme operating conditions may occur, which may bring about the thermal stress, deformation, shafting vibration and stability of the shaft system. It is a key technical problem to improve the operation safety of large capacity thermal power unit under the condition of wide range load rapid change.
The problem of operation safety and stability caused by the participation of large capacity thermal power unit in peak regulation is more prominent in our country. The reason is that the conditions on both sides of the machine network are different from the western countries, but this aspect is still lacking in deep research. In this paper, the 600MW Turbo generator set is the object of the large capacity thermal power unit, and the state and enterprise are in the state and enterprise. Under the support of scientific and technological projects, it is of great importance to study the dynamic characteristics and stability of the shaft system under the condition of large variable load operation, the vibration characteristics and the method of fault feature extraction under the condition of failure. It is of great importance to improve the safety and reliability of the unit to participate in the operation of peak regulation.
The main contents and achievements of this paper are as follows:
(1) analysis of the structure and operation characteristics of 600MW unit. Combined with two detailed rules, this paper analyzes the influence of AGC running formula on the life of steam turbine, the vibration characteristics of materials and shafting, and describes the technical status of the vibration monitoring and protection system of large capacity thermal power unit (TSI system and TDM system), and the actual operation of a 600MW subcritical thermal power unit. The data analyzed the disturbance of turbine shafting vibration under the operating mode of automatic generation control (AGC), unit load, main steam pressure, and main steam flow change. From the long-term trend of operation data, the rapid change load of the unit has a definite influence on the vibration of the bearing at both ends of the high and high pressure cylinder. It has no obvious effect on vibration signal waveform and spectrum structure, and does not change the vibration state of high and medium pressure rotor.
(2) the calculation and analysis of the vibration characteristics of the shaft system. Taking the domestic typical 600MW thermal power unit as the object, the natural characteristics of the bending vibration and torsional vibration of the shaft system, the torsional vibration response characteristic of the shaft system under the fast load condition and the response characteristic of the axial torsional vibration under the two phase short circuit fault of the generator are simulated and compared. The analysis results show that the torsional vibration hazard axis of the shaft system of the 600MW unit is located in the connection position between the rotors. In the fast lifting and lifting load, the torque response of the shaft system presents a attenuation oscillation characteristic, which indicates that the shaft is in a stable state at the rapid load rise, and the first and two natural frequencies of the torsional vibration in the two phase short circuit fault are in the torque response. The peak value is the most prominent, the power frequency and its two harmonics are also obvious, and there is a resonance risk. Therefore, the two phase short circuit fault has great influence on the safety of shafting.
(3) the abnormal vibration analysis of the shaft system in the transient process of the steam turbine. Through the actual case, the abnormal vibration phenomenon of the large capacity thermal power unit is analyzed, the response characteristic of the abnormal vibration is discussed, the signal analysis method of extracting the characteristics of the fault is studied to provide the basis for the fault diagnosis of the shaft system. The high school pressure rotor of a 600MW unit is studied. The cause of the thermal deformation of the rotor is determined by the vibration characteristics of the slow thermal deformation. A method based on the Gabor transform time frequency domain filtering is proposed to extract the special frequency components of the vibration signals and carry out the analysis of the stability of the shafting and the fault judgment. The analysis of the signal proves the effect of the method.
(4) study on the fault monitoring and diagnosis method of the Turbine rubbing fault. The fault information in the relative axis vibration response signal is very weak when the turbine generator unit occurs a slight moving and static part rubbing fault. A new method of monitoring and diagnosis of the rubbing fault is proposed by combining the structural vibration detection with the signal analysis and processing. The high frequency shock vibration energy information is applied to the abnormal vibration with instantaneous impact characteristics of the rubbing. Due to the insensitivity of the relative axial vibration monitoring to the impact vibration response caused by the rubbing, a method of wavelet singular value detection for the impact failure of the rubbing is proposed, and the wavelet multi-resolution analysis is used to obtain the specific scale on the specific scale. The instantaneous impact signal of the rubbing is extracted and the amplitude envelope of the instantaneous shock signal is extracted. Then the wavelet singular value detection method is used to detect the mutation information caused by the rubbing, which can obviously improve the extraction effect of the characteristics of the weak rubbing fault.
(5) the blind separation method of the steam turbine vibration source. The frequency domain ICA analysis method is used to separate the multi channel vibration signal source of the multi channel shaft vibration signal. The result shows that the frequency domain ICA can give the description of the source signal more clearly. The separation result is more consistent with the actual situation of the vibration source of the turbine rotor system. The frequency domain ICA can be separated. The physical meaning of the separation results is clear and clear. The ICA feature extraction method using the single channel vibration measured signal is studied. The results show that the base function separated by only single channel ICA is not enough to reflect the change of the operating state of the unit. A base function is processed to verify its effectiveness as feature information.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM311

【参考文献】